Hot rolling oil for steel

ABSTRACT

The present invention relates to a composition of oil suitable for hot rolling of steel and its alloys. The oil composition forms an oil-in-water dispersion when mixed with water using proper agitation and provides adequate lubricity and load carrying capacity during rolling of steel slab/sheets.

FIELD OF THE INVENTION

This invention relates to a composition of oil suitable for hot rolling of steel and its alloys. The oil composition forms an oil-in-water dispersion when mixed with water using proper agitation and provides adequate lubricity and load carrying capacity during rolling of steel slab/sheets.

BACKGROUND OF THE INVENTION

It takes many steps to create steel. The hot rolling process is one of them. This process reheats, rolls and coils the steel. In metal working, rolling is a metal forming process in which metal stock is passed through a pair of rolls. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its recrystallization temperature, then the process is termed as hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is termed as cold rolling. In terms of usage, hot rolling processes more tonnage than any other manufacturing process.

The primary function of the Hot Strip Mill is to reheat semi-finished steel slabs of steel nearly to their melting point, then roll them thinner and longer through successive rolling mill stands driven by motors and finally coiling up the lengthened steel sheet for transport to the next process. In conventional hot strip production, slabs of thickness of about 250 mm are heated in a furnace and are reduced to 30 to 60 mm in thickness after passing through the roughing mill, and then further reducing it to within a range of 0.8 to 25.4 mm by rolling in the finishing mill.

Examples of hot rolled products are rails, structurals, concrete reinforcing bars, wire rods, plates, sheet and strip. The plates, sheet and strip products are used to manufacture pipes and tubes, construction materials and body panels and stampings for the appliance and automotive industries.

The temperature encountered in the hot rolling operation estimated to be very high. It is therefore essential to provide a means of controlling the temperature of the rolls in order to improve their life. Cooling is therefore necessary to control the temperature of the work rolls and at the same time lubrication is equally important for preventing the metal-to-metal contact between work rolls and the work piece. The hot rolling oil is, therefore, required to fulfil two key properties i.e., lubrication and cooling. For these reasons dispersion of oil in water are preferred for the use of hot rolling operations as cooling properties is derived through water while oil separated from dispersion during use provide necessary lubrication requirement.

Hot rolling oil is the application of a dispersion, which is a mechanical mixture of oil (>1%) and water (<99%) in the hot rolling process. The typical application involves 40-50 litres per minute at 5 bar. Oil is injected into the water stream and mixed by a static tube mixer to form dispersion that is sprayed onto the work roll/backup roll. The goal is to form a strong lubricating film on the roll surface. The most important function of the rolling lubricant is to reduce the coefficient of friction during the actual rolling to the desired level. The better surface finish of the rolled product which is largely dependent on the rolling oil formulation is the customer requirement.

One of the primary requirements of a lubricant is that it must be capable of wetting and adhering to the surface to be lubricated. A good dispersion of hot rolling oil should provide desired lubrication to the metal as it passes through the rolls, reduce roll wear, provide sufficient cooling to the rolls and metals, improve strip quality and eliminate edge seam/scale defects. Moreover, a good dispersion also increases productivity through extended campaign length, prevents work-roll cost, has the ability to roll harder grades with restricted power loads and as a result reduces power consumption. At the same time, a good dispersion also decreases maintenance costs.

U.S. Pat. No. 4,978,465 discloses improved sulfurized metalworking lubricants derived from natural fats and oils which are modified by reacting the natural fat or oil with a hindered polyol and a dicarboxylic acid are provided. The sulfurized blends of said modified fats and oils with fatty acid esters and lubricant compositions are useful for a variety of metalworking applications wherein the sulfurized modified triglycerides or sulfurized blends are combined with other lubricating agents, emulsifiers and additives.

WO2011117892A2 discloses a composition of oil suitable for steel sheet rolling. This oil is comprised of natural fats/oils, synthetic esters, high viscosity index premium quality mineral oils and other performance additives such as extreme pressure, antiwear, emulsifiers, dispersant, antioxidants etc. The oil composition forms metastable oil-in-water emulsion with slight to moderate agitation.

The prior art references disclose oil in water dispersions containing metal rolling oil composition and water. However, conventional emulsifier/s is/are used as important component/s in the composition. In the present invention, the aim is to develop a hot rolling oil composition without the use of conventional emulsifier/s for better oil in water dispersion.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a hot rolling oil composition comprising: an oil in water dispersion, wherein the oil is selected from the group consisting of a fatty oil, or a synthetic ester, or a combination thereof, and optionally a fatty acid, base oil, or a combination thereof and 1-12% w/w of sulfurized fatty oil, or sulfurized ester or a combination thereof, the hot rolling oil composition comprises 0.1 to 2.0% w/w of sulphur content in said composition, wherein the dispersion of hot rolling oil composition in water is having emulsion stability index (ESI) in the range of 0.05-0.25 and load carrying capacity of 2000-3000 lbs.

In an embodiment of the present invention, the total sulphur content in the composition is in the range of 1.0 to1.1% w/w.

In another embodiment of the present invention, the amount of fatty oils or synthetic esters or a combination thereof ranges from about 20% to 90% w/w of the composition.

In further another embodiment of the present invention, the amount of fatty acids ranges from about 0-15% w/w.

In still another embodiment of the present invention, the amount of base oil ranges from about 0-75% w/w.

In yet another embodiment of the present invention, sulfurized fatty oil or sulfurized synthetic ester ranges from 1-12% w/w.

In yet another embodiment of the present invention, a synergistic and direct correlation exists between load carrying capacity of oil i.e., Falex Jaw Load and Emulsion Stability Index (ESI) up to 0.25.

In yet another embodiment of the present invention, the friction coefficient of neat hot rolling is 0.09 to 0.12.

In yet another embodiment of the present invention, the sulfurized fatty oil is derived from palm oil, soya oil, lard oil, sunflower oil, corn oil, soybean oil, rapeseed oil, peanut oil, olive oil, canola oil, cottonseed oil, castor oil, turpentine oil, toll oil, or a combination thereof.

In one another embodiment of the present invention, the sulfurized synthetic ester is selected from Dover Chemical's lard oil and esters selected from Base LOSE, Base 101, Mayco Base 1351, Mayco Base 1210, Sulperm 18 and Base 44; Additin 4412F, Additin RC 2310, Additin RC2410 and Additin RC2526 from Rhein Chemie; King Industry's fatty acid ester NA-LUBE EP-5210, NA-LUBE EP-5216; Fatty Oil Ester or Fatty oil: NA-LUBE EP-5310, NA-LUBE EP-5316; Olefins or Fatty Oil: NA-LUBE EP-5415, NA-LUBE EP-5425; Vegetable polysulphides sulfurized esters VPS 11, VPS 15 and VPS17 of Arkema, INC.; Synester SE 110 and synester SE 115 of Lubrizol.

In further another embodiment of the present invention, the base oil is a lubricant base selected from Group I, II, III or IV base stocks or combination thereof.

In still another embodiment of the present invention, the hot rolling oil may further comprising conventional additives such as free fatty acids like oleic acid, stearic acid, antioxidant containing amine, phenolic group, silicone containing antifoam.

In another embodiment of the present invention, the fatty oils are selected from palm oil, coconut oil, karanjea oil, rapeseed oil and tallow.

In yet another embodiment of the present invention, the synthetic esters are selected from butyl stearate, PEG ester, sorbitan ester, glycerol ester, TMP trioleate, penta erytritoldioleate and tetraoleate.

In further another embodiment of the present invention, the oil in water dispersion comprises about 5% w/w or less of the rolling oil composition of any of the preceding claims and about 95% w/w or high of water.

In still another embodiment of the present invention, the dispersion does not contain any conventional emulsifier to make oil in water dispersion to get desire emulsion stability index (ESI) of 0.05-0.25.

DESCRIPTION OF THE INVENTION

The present invention discloses a composition of oil suitable for hot rolling of steel and its alloys. The present invention also discloses the process of preparation of oil composition and its oil in water dispersion suitable for hot rolling of steel and its alloys.

Sulfurized fatty oils and esters are good extreme pressure additive. The amount of sulfur provided to the lubricating oil composition will depend upon the sulfur content of the sulfurized fatty oil/s or ester or their mixtures and the amount added to the composition.

The present invention discloses a hot rolling oil composition comprising oil selected from the group comprising of a fatty oil and/or a synthetic ester, and combination thereof; sulfurized fatty oil and or sulfurized fatty ester and combination thereof and optionally a fatty acid, or a base oil, or mixtures thereof; wherein, the hot rolling oil composition comprises 0.1 to 2.0% w/w of sulphur content in said composition. The said oil composition may also contain other common additives like antioxidant, antifoam, VI improver and mixtures thereof.

In an embodiment, a hot rolling oil composition for steel and/or its alloys is disclosed, such composition comprising 20% to 90% w/w fatty oil and/or synthetic ester, 0-15% w/w fatty acid, 0-75% w/w base oil, and 1%-12% w/w of sulfurized fatty oil and/or sulfurized ester.

In accordance with the present invention, the base oil is a lubricant base selected from Group I, II, III or IV base stocks or mixtures thereof. The fatty oil is selected from palm oil, coconut oil, karanjea oil, rapeseed oil, tallow etc. and mixtures thereof. The synthetic ester is selected from butyl stearate, PEG ester, sorbitan ester, glycerol ester, TMP trioleate, pentaerytritoldioleate & tetraoleate, etc. and combination thereof.

In accordance with the present invention, the total sulphur content in the said hot rolling oil composition is in the range of 0.1 to 2.0% w/w, preferably in the range of 1.0% to 1.1% w/w. In an embodiment of the present invention, one source of sulphur is sulfurized fatty oil. The sulfurized fatty oil is derived from palm oil, soya oil, lard oil, sunflower oil, corn oil, soybean oil, rapeseed oil, peanut oil, olive oil, canola oil, cottonseed oil, castor oil, turpentine oil, tall oil, or combination thereof.

In another embodiment, another source of sulphur is sulfurized synthetic ester. In accordance with the present invention, the sulfurized synthetic ester is selected from Dover Chemical's additives like Base LOSE, Base 101, Mayco Base 1351, Mayco Base 1210, Sulperm 18 and Base 44; Additin 4412F, Additin RC 2310, Additin RC2410 and Additin RC2526 from Rhein Chemie; King Industry's fatty acid ester NA-LUBE EP-5210, NA-LUBE EP-5216; Fatty Oil Ester/Fatty oil: NA-LUBE EP-5310, NA-LUBE EP-5316; Olefin/Fatty Oil: NA-LUBE EP-5415, NA-LUBE EP-5425; Vegetable polysulphides sulfurized esters VPS 11, VPS 15 and VPS17 of Arkema, INC.; Synester SE 110 and synester SE 115 of Lubrizol.

The maximum lubrication and load carrying property was observed when the sulphur content in the said composition was in the range of 1.0-1.1% w/w.

The present invention also discloses an oil in water dispersion comprising 5% w/w of the rolling oil composition in accordance with the present invention and about 95% w/w of water. In an embodiment, the dispersion has an emulsion stability index (ESI) in the range of 0.05-0.25. The Emulsion Stability Index (ESI) is used to determine the dispersion stability.

In accordance with the present invention, the dispersion does not contain any conventional emulsifier, such as ethylene oxide, propylene oxide or its condensate, amine ethoxylate, alcohol ethoxilate, sulphonate, copolymers of propylene glycol and ethylene glycol, poly alcohols, poly oxyethylene alcohol ether, poly oxyethylenenonyl phenyl ether and the like.

It can be appreciated that only combination of oils of lubricating viscosity and sulfurized fatty oil/s or Esters or their mixtures is not sufficient for making good quality steel hot rolling oil. Therefore, an optimized combination of above two were selected based on the chemistry to get a composition of rolling oil suitable for hot rolling of steel and its alloy.

To prepare the hot rolling oil composition in accordance with the present invention, the base oil is heated to 45-50° C. with stirring. The hot rolling oil phase is prepared by adding the fatty oil/s or synthetic ester/s or their combination, fatty acid, antiwear and extreme pressure additives, sulfurized fatty oil or esters or their combination, antioxidant to the base oil one after another under stirring condition. Reasonable time 5-10 minutes for each additive) is given to dissolve one additive before addition of the next additive.

After addition of the final additive, the rolling oil blend is stirred for another 30 minutes with stirring and heating at 45-50° C. Ordinary Remi stirrer can be used for the stirring and dissolving the additives to the base oil. Precaution must be taken for avoiding excessive heating (>60° C.) of the oil phase. The water used to make the dispersion is 200 ppm hard water as CaCO3 which is prepared by dissolving required quantity of anhydrous CaCl₂, MgSO₄H₂O and NaHCO₃ in distilled water and adjusting the pH to 6.5-7.5.

The dispersion characteristics is evaluated by addition of 5% hot rolling oil phase to the water phase (total 200 ml dispersion) at 50° C. and stirring the dispersion under high shear @ 11000 rpm for 2 minutes with a homogenizer and pouring the dispersion in a 400 ml graduated glass column immediately after preparation and kept it in an air oven of 50° C. for 30 minutes and find out the oil content of 100 ml each of top and bottom phase of 200 ml dispersion. The emulsion stability index (ESI) is the ratio of oil content of bottom phase to the top phase. Emulsion stability index (ESI) of the present invention is in the range of 0.05-0.25, demonstrating excellent lubrication property of the hot rolling oil composition.

The lubrication property of the formulations can be evaluated in terms of friction coefficient of neat rolling oil, and Falex Jaw Load (Load Carrying Capacity of the rolling Oil) of rolling oil in water dispersion. This is carried out as per ASTM D-6425 (friction coefficient) and ASTM-D 3233 (Falex Jaw Load). Good hot rolling oil is characterized by optimum friction coefficient (lubrication) and high Falex Jaw Load (load carrying capacity).

Having described the basic aspects of the present invention, the following non-limiting examples illustrate specific embodiment thereof

EXAMPLE 1

Hot rolling oil compositions with varying amount of individual components were prepared in accordance with the present invention. The Emulsion Stability Index (ESI) was determined by measuring the ratio of oil content from 100 ml dispersions from each of the top and bottom phase of total 200 ml dispersion after 30 minutes. The dispersion is splitted by 10-15 ml concentrated hydrochloric acid in a special emulsion splitting flask having minimum 0.1 ml graduation at the narrow top.

The determination Coefficient of Friction and Falex Jaw Load (Load Carrying Capacity of the rolling Oil) is carried out as per ASTM D-6425 (friction coefficient) and ASTM- D 3233 (Falex Jaw Load). The results of the three tests are depicted in TABLE 1.

TABLE 1 Total Sulphur Coefficient Content in of Friction Sulphurized Sulphurized Sulphur for Neat Falex Jaw Fatty oil/s or Fatty oil/s or content in Emulsion Oil (300N, load, lbs. Other ester/s or their ester/s or their the final Stability 50 Hz., 1 mm, (5% oil in S. Ingredients combination combination formulation Index 50-150° C., water No. % wt. % wt. (% wt.) % wt. (ESI) 1 Hr.) dispersion) Remarks 1. 16 rapeseed 0.5 10 0.05 0.03 seizure 1600 Poor oil, 2 palm sulfurized formulation oil, 81.5 fatty oil -1 base oil, 0.5 antioxidant 2. 26 rapeseed 10Sulfurised 10 1.0 0.14 0.10 2500 Very oil, 44 palm fatty oil -1 Good oil, 19.5 formulation. base oil, 0.5 antioxidant 3. 15 TMP 5 sulfurized 16 0.80 0.06 0.11 2300 Good trioleate, synthetic formulation 35 karanja ester -1 oil, 10 oleic acid, 1antioxidant, base oil 34 4. 85 castor 5 Sulfurized 18% 0.90 0.02 0.11 1400 Poor oil + 10 synthetic formulation rapeseed oil ester-2 5. 20 ground nut 6.0 18.0 1.08 0.20 0.09 2800 Excellent oil, 7.99 (combination formulation Pentaerythritol of sulfurized tetraoleate,, fatty oil 2 + 60 coconut oil, sulfurized 6 stearic acid, synthetic 0.0 ester 3) 1% silicone antifoam 6. 30 rapeseed 0.5 16.0 0.08 0.01 0.12 1600 Poor oil, 10 (combination Combination Penta- of sulfurized erythritoldiolease, fatty oil 1 + 59.5 base oil sulfurized synthetic ester 1) 7. 85 coconut, 5 14 0.70 0.30 0.11 2200 Falex 9 palm, 1 (combination jaw sorbitan ester of sulfurized load synthetic decreased ester 3 + as ESI sulfurized is >0.25 synthetic ester 4) 8. 70 coconut 10.0 10.5 1.05 0.22 0.09 2800 Excellent Oil, 10.5 (sulfurized Combination TMP trioleate, fatty oil 2) 9.4% oleic acid, 0.1 silicone antifoam 9. 69.9 coconut 5.0 17.6 0.88 0.16 0.10 2600 Very oil, 14 butyl (combination good stearate, 1 of two combination oleic acid, 1 additives) antioxidant, 0.1 antifoam 10. 65 Rapeseed 15.0 16.0 2.40 0.03 0.12 1800 Poor oil + 15 (combination Combination base oil + of three 5 butyl additives) stearate 

We claim:
 1. A hot rolling oil composition comprising: an oil in water dispersion, wherein the oil is selected from the group consisting of a fatty oil, or a synthetic ester, or a combination thereof, and optionally a fatty acid, base oil, or a combination thereof and 1-12% w/w of sulfurized fatty oil, or sulfurized ester or a combination thereof, the hot rolling oil composition comprises 0.1 to 2.0% w/w of sulphur content in said composition, wherein the dispersion of hot rolling oil composition in water is having emulsion stability index (ESI) in the range of 0.05-0.25 and load carrying capacity of 2000-3000 lbs.
 2. The hot rolling oil composition of claim 1, wherein the total sulphur content in the composition is in the range of 1.0 to 1.1% w/w.
 3. The hot rolling oil composition of claim 1, wherein the amount of fatty oils or synthetic esters, or a combination thereof ranges from about 20% to 90% w/w of the composition.
 4. The hot rolling oil composition of claim 1, wherein the amount of fatty acids ranges from 0-15% w/w.
 5. The hot rolling oil composition of claim 1, wherein the amount of base oil ranges from 0-75% w/w.
 6. The hot rolling oil composition of claim 1, wherein a synergistic and direct correlation exists between load carrying capacity of oil i.e., Falex Jaw Load and Emulsion Stability Index (ESI) up to 0.25.
 7. The hot rolling oil composition of claim 1, wherein the friction coefficient of neat hot rolling is 0.09 to 0.12.
 8. The hot rolling oil composition of claim 1, wherein the sulfurized fatty oil is derived from palm oil, soya oil, lard oil, sunflower oil, corn oil, soybean oil, rapeseed oil, peanut oil, olive oil, canola oil, cottonseed oil, castor oil, turpentine oil, toll oil, or a combination thereof.
 9. The hot rolling oil composition of claim 1, wherein the sulfurized synthetic ester is selected from Dover Chemical's lard oil and esters selected from Base 10SE, Base 101, Mayco Base 1351, Mayco Base 1210, Sulperm 18 and Base 44, Additin 4412F, Additin RC 2310, Additin RC2410 and Additin RC2526 from RheinChemie; King Industry's fatty acid ester NA-LUBE EP-5210, NA-LUBE EP-5216, Fatty Oil Ester or Fatty oil, NA-LUBE EP-5310, NA-LUBE EP-5316, Olefins or Fatty Oil: NA-LUBE EP-5415, NA-LUBE EP-5425; Vegetable polysulfides sulfurized esters VPS 11, VPS 15 and VPS17 of Arkema, INC.; Synester SE 110 and synester SE 115 of Lubrizol.
 10. The hot rolling oil composition of claim 1, wherein the base oil is a lubricant base selected from Group I, II, III or IV base stocks or combination thereof.
 11. The hot rolling oil composition of claim 1, further comprising conventional additives such as free fatty acids like oleic acid, stearic acid, antioxidant containing amine, phenolic group and silicone containing antifoam.
 12. The hot rolling oil composition of claim 1, wherein the fatty oils are selected from palm oil, coconut oil, karanjea oil, rapeseed oil and tallow.
 13. The hot rolling oil composition of claim 1, wherein the synthetic esters are selected from butyl stearate, PEG ester, sorbitan ester, glycerol ester, TMP trioleate, pentaerytritoldioleateand tetraoleate.
 14. The hot rolling oil composition of claim 1, wherein the oil in water dispersion comprises about 5% w/w or less of the rolling oil composition of any of the preceding claims and about 95% w/w or higher of water.
 15. The oil in water dispersion of claim 14, wherein the dispersion does not contain any conventional emulsifier to make an oil in water dispersion having Emulsion Stability Index (ESI) of 0.05-0.25. 